U.S. Pat. No. 3,689,862 to Hilgers discloses inductor coils with mechanically coupleable bobbins in which the bobbin of each coil comprises a tubular barrel, larger and smaller end flanges on axially opposite ends of the barrel and rendering the bore closed and open at its larger and smaller flange ends, a raised non-circular rib on the outside of the larger flange and enclosing a region matching the configuration of the smaller flange, and a pin coaxial with and projecting from the larger flange and of slightly smaller size than the bore of the barrel. In use, two or more similar bobbins are placed coaxially to form a bobbin array in which, say, the pins of the bobbins extend leftward. The bobbins in the array are then assembled by inserting each bobbin pin having a bobbin to its left into the base of the leftward bobbin, and by inserting the small flange of each bobbin having one to its right into the region enclosed by the raised rib on the rightward bobbin. When so assembled, the bobbins in the array are coupled for common rotation. The Hilgers patent discloses that inductance coils can then be formed by rotating the bobbins together (by undisclosed means) to cause individual wires to be wound as coils on the bobbins in the array.
The inductor coils of the Hilgers patent have the disadvantages among others that their pins are, upon separation of the bobbins, superfluous and wasteful of material and space and can create problems in mounting the inductor coils other than in the stacked relation taught by Hilgers. Moreover, the mode of coupling the bobbins together by having the entire smaller flange of one bobbin received within a region enclosed by the raised rib on the larger flange of another is wasteful of bobbin material. A further disadvantage is that, when an array of the Hilgers bobbins are assembled as described, the bobbins are maintained in angular alignment only by the closeness of fit between their assembled pins and bores but, if there is any angular play therebetween, such play accumulates over the array of bobbins as a function of their number. The result is that the number of bobbins which can be included in such an array without exceeding a limit for angular play per bobbin which is prescribed in connection with, say, the winding of wires individually on the bobbins is a number which is inherently restricted.